**3. Methods for the separation of ions in aqueous solution**

In the literature, various methods for the separation of ions and cations (solute) in aqueous solution (solvent) exist. Selection of the process depends on the purity or degree of recovery that is required for both the solvent and the solute. Nowadays there are processes ranging from adsorption processes using activated carbon, which is one of the most economical materials, to reverse osmosis processes [8].

There are various chemical causes or reasons by which materials are related to ions or cations, among them attraction forces or electrostatic repulsions (mainly present in inorganic compounds), dispersive forces, or π-π interactions (organic compounds such as organic matter) stand out [9].

**81**

*Nutritive Solutions Formulated from Organic Fertilizers DOI: http://dx.doi.org/10.5772/intechopen.89955*

used in Mexico and other countries is activated carbon.

), nitrate (NO3

solution according to each crop's needs.

**4. Safety of organic materials**

potassium (K+

tion process [12, 13].

**4.1 Heavy metals**

**4.2 Pathogens**

excrement products.

Among the materials used for the retention of inorganic compounds such as metals, metalloids, and heavy metals include activated carbons, zeolites, clays, lignocellulosic materials, carbon nanotubes, composites from green materials such as mixed cellulose with iron oxides and also can be used an ion exchange resins and membranes [10, 11]. In the case of organic compounds, the material traditionally

A process that could be applied in the separation of ions and cations from organic fertilizers' derived mixture and whose main components are essentially

<sup>−</sup>), and phosphate (PO4

matter content, which are an "interference" in the separation processes due to its high degree of complexity in the chemical structure, would be a sequential adsorp-

Therefore, as an ideal process for the elimination of this type of "interference" and the possible recovery of the ions and cations of interest, a cycle of separations must be done. First, the ion mixture must be placed in contact with carbon-based materials (this material already impregnated with that organic material can also be used for fertilizer) followed by cycles of adsorption columns with special ion exchange resins for each one of the ions. With this process, we can recover each of the components of the mixture and allocate them to the preparation of a nutrient

The main concern associated with the use of organic materials is mainly related to the possible presence of unwanted components, such as microbial pathogens, heavy metals, organic pollutants, waste pharmaceuticals, and personal care products, which threaten public health when undertreated. For example, organic materials could contain pesticide residues if obtained from some crop residues or

The problem with regard to heavy metals is one of the most studied, and there is a vast literature dedicated to the subject. It is well known that concentrations of heavy metals above certain limits can lead to crop toxicity and may enter the food chain. The contents of MP in organic materials is very varied, since it depends on several factors, including the origin of the product, the feeding of livestock, etc. Rodriguez et al. [14] report the following total concentrations of heavy metals in cattle compost (in ppm): As 2.0 (−0.3), Cd 0.21 (−0.06), Hg <0.01, and Pb 5.9 (−1.01) and, for bovine lombricompost (in ppm), As 3.6 (−0.90), Cd 0.46 (−0.10), Hg <0.01, and Pb 16 (−2.60). For its part, Pane et al. [15] report the following heavy metal content in artichoke compost that was used to obtain nutrient solutions (78.0% artichoke, 20% woodchips, and 2% mature compost) (in ppm): Cd 0.38, Cr

Depending on the source of the original material, the risks of contamination of unwanted organisms, such as pathogens, vary and are the highest in wastewater and

Organic fertilizer production processes eliminate many pathogens as they include inactivation mechanisms such as very high temperatures, solar

antibiotics used in the diets of breeding animals, if excrement is used.

20.69, Cu 21.01, Pb 13.45, Zn 13.45, and Zn 70.50, all below legal limits.

<sup>−</sup>) mixed with high organic

*Nutritive Solutions Formulated from Organic Fertilizers DOI: http://dx.doi.org/10.5772/intechopen.89955*

*Urban Horticulture - Necessity of the Future*

**Figure 5.**

**80**

**Table 3.**

**3. Methods for the separation of ions in aqueous solution**

*Macro- and micronutrient content in some organic nutrient solutions.*

*(1) Pant [5]; (2) Pant (2011); (3) González et al. [6]; (4) Ochoa et al. [7]. OM = organic material; VCG = vermicompost poultry manure; VCG = vermicompost poultry manure; CBv = compost bovine*

compounds such as organic matter) stand out [9].

In the literature, various methods for the separation of ions and cations (solute) in aqueous solution (solvent) exist. Selection of the process depends on the purity or degree of recovery that is required for both the solvent and the solute. Nowadays there are processes ranging from adsorption processes using activated carbon, which is one of the most economical materials, to reverse osmosis processes [8]. There are various chemical causes or reasons by which materials are related to ions or cations, among them attraction forces or electrostatic repulsions (mainly present in inorganic compounds), dispersive forces, or π-π interactions (organic

*Twenty days after transplanting baby lettuce produced with chemical synthetic fertilizer (A) and manure* 

**Author 1 2 3 4 Steiner solution Sánchez**

OM VCG VCP P + B VCB — — Dilution 1:10 1:10 1:6 1:20 — — EC dS m<sup>−</sup><sup>1</sup> 2 2 4 1 2 2

N 74.9 81.7 313.87 219 168 200 P 16.2 16.2 20.01 18.2 31 60 K 166.6 180.4 174.91 230 273 250 Ca 486 49 41.12 1.32 180 200 Mg 42.8 43.9 32.94 520 48 60 S — 54.40 — 336 200 Fe — — — 0.49 — 1 Cu — — — 0.13 — 0.01 Mn — — — 0.089 — 0.7 Zn — — — 0.19 — 0.01

mg L<sup>−</sup><sup>1</sup>

*.*

**References**

*extract (B). Both cultivated in floating root system with pH 6 and EC = 1.5 dS m<sup>−</sup><sup>1</sup>*

Among the materials used for the retention of inorganic compounds such as metals, metalloids, and heavy metals include activated carbons, zeolites, clays, lignocellulosic materials, carbon nanotubes, composites from green materials such as mixed cellulose with iron oxides and also can be used an ion exchange resins and membranes [10, 11]. In the case of organic compounds, the material traditionally used in Mexico and other countries is activated carbon.

A process that could be applied in the separation of ions and cations from organic fertilizers' derived mixture and whose main components are essentially potassium (K+ ), nitrate (NO3 <sup>−</sup>), and phosphate (PO4 <sup>−</sup>) mixed with high organic matter content, which are an "interference" in the separation processes due to its high degree of complexity in the chemical structure, would be a sequential adsorption process [12, 13].

Therefore, as an ideal process for the elimination of this type of "interference" and the possible recovery of the ions and cations of interest, a cycle of separations must be done. First, the ion mixture must be placed in contact with carbon-based materials (this material already impregnated with that organic material can also be used for fertilizer) followed by cycles of adsorption columns with special ion exchange resins for each one of the ions. With this process, we can recover each of the components of the mixture and allocate them to the preparation of a nutrient solution according to each crop's needs.
